[svn-commits] dvossel: branch dvossel/hd_confbridge r310239 - /team/dvossel/hd_confbridge/b...
SVN commits to the Digium repositories
svn-commits at lists.digium.com
Thu Mar 10 09:35:48 CST 2011
Author: dvossel
Date: Thu Mar 10 09:35:44 2011
New Revision: 310239
URL: http://svnview.digium.com/svn/asterisk?view=rev&rev=310239
Log:
Improving comments and code clarity in the softmix thread code.
Modified:
team/dvossel/hd_confbridge/bridges/bridge_softmix.c
Modified: team/dvossel/hd_confbridge/bridges/bridge_softmix.c
URL: http://svnview.digium.com/svn/asterisk/team/dvossel/hd_confbridge/bridges/bridge_softmix.c?view=diff&rev=310239&r1=310238&r2=310239
==============================================================================
--- team/dvossel/hd_confbridge/bridges/bridge_softmix.c (original)
+++ team/dvossel/hd_confbridge/bridges/bridge_softmix.c Thu Mar 10 09:35:44 2011
@@ -461,17 +461,32 @@
unsigned int best_rate = stats->highest_supported_rate;
int best_index = -1;
- /* 1. pick the best sample rate two or more channels support
- * 2. if two or more channels do not support the same rate, pick the
- * lowest sample rate that is still above the internal rate. */
- for (i = 0; ((i < ARRAY_LEN(stats->num_channels)) && stats->num_channels[i]); i++) {
- if ((stats->num_channels[i] >= 2 && (best_index == -1)) ||
- ((best_index != -1) &&
+ for (i = 0; i < ARRAY_LEN(stats->num_channels); i++) {
+ if (stats->num_channels[i]) {
+ break;
+ }
+ /* best_rate starts out being the first sample rate
+ * greater than the internal sample rate that 2 or
+ * more channels support. */
+ if (stats->num_channels[i] >= 2 && (best_index == -1)) {
+ best_rate = stats->sample_rates[i];
+ best_index = i;
+ /* If it has been detected that multiple rates above
+ * the internal rate are present, compare those rates
+ * to each other and pick the highest one two or more
+ * channels support. */
+ } else if (((best_index != -1) &&
(stats->num_channels[i] >= 2) &&
(stats->sample_rates[best_index] < stats->sample_rates[i]))) {
-
best_rate = stats->sample_rates[i];
best_index = i;
+ /* It is possible that multiple channels exist with native sample
+ * rates above the internal sample rate, but none of those channels
+ * have the same rate in common. In this case, the lowest sample
+ * rate among those channels is picked. Over time as additional
+ * statistic runs are made the internal sample rate number will
+ * adjust to the most optimal sample rate, but it may take multiple
+ * iterations. */
} else if (best_index == -1) {
best_rate = MIN(best_rate, stats->sample_rates[i]);
}
@@ -481,7 +496,7 @@
bridge_data->internal_rate = best_rate;
return 1;
} else if (!stats->num_at_internal_rate && !stats->num_above_internal_rate) {
- /* in this case, the highest supported rate is actually lower than the internal rate */
+ /* In this case, the highest supported rate is actually lower than the internal rate */
bridge_data->internal_rate = stats->highest_supported_rate;
ast_debug(1, " Bridge changed from %d to %d\n", bridge_data->internal_rate, stats->highest_supported_rate);
return 1;
@@ -540,16 +555,14 @@
ao2_ref(bridge_data, 1);
timer = bridge_data->timer;
timingfd = ast_timer_fd(timer);
-
- /* give it room to grow, memory is cheap but allocations are expensive */
+ softmix_translate_helper_init(&trans_helper, bridge_data->internal_rate);
+ ast_timer_set_rate(timer, (1000 / SOFTMIX_INTERVAL));
+
+ /* Give the mixing array room to grow, memory is cheap but allocations are expensive. */
if (softmix_mixing_array_init(&mixing_array, bridge->num + 10)) {
ast_log(LOG_NOTICE, "Failed to allocate softmix mixing structure. \n");
goto softmix_cleanup;
}
-
- softmix_translate_helper_init(&trans_helper, bridge_data->internal_rate);
-
- ast_timer_set_rate(timer, (1000 / SOFTMIX_INTERVAL));
while (!bridge->stop && !bridge->refresh && bridge->array_num) {
struct ast_bridge_channel *bridge_channel = NULL;
@@ -559,25 +572,30 @@
unsigned int softmix_datalen = SOFTMIX_DATALEN(bridge_data->internal_rate);
if (softmix_datalen > MAX_DATALEN) {
- /* This should NEVER happen, but if it does we need to know about it. */
+ /* This should NEVER happen, but if it does we need to know about it. Almost
+ * all the memcpys used during this process depend on this assumption. Rather
+ * than checking this over and over again through out the code, this single
+ * verification is done on each iteration. */
ast_log(LOG_WARNING, "Conference mixing error, requested mixing length greater than mixing buffer.\n");
goto softmix_cleanup;
}
- /* If the number of participants in the bridge has changed, the mixing array
- * buffer must realloc */
+
+ /* Grow the mixing array buffer as participants are added. */
if (mixing_array.max_num_entries < bridge->num && softmix_mixing_array_grow(&mixing_array, bridge->num + 5)) {
goto softmix_cleanup;
}
+
+ /* init the number of buffers stored in the mixing array to 0.
+ * As buffers are added for mixing, this number is incremented. */
mixing_array.used_entries = 0;
- /* these variables help determine if a rate change is required */
+ /* These variables help determine if a rate change is required */
if (!stat_iteration_counter) {
memset(&stats, 0, sizeof(stats));
- /* If the bridge has an internal sample rate set, we must lock in on that rate */
stats.locked_rate = bridge->internal_sample_rate;
}
- /* if the sample rate has changed, update the translator helper */
+ /* If the sample rate has changed, update the translator helper */
if (update_all_rates) {
softmix_translate_helper_change_rate(&trans_helper, bridge_data->internal_rate);
}
@@ -591,24 +609,23 @@
set_softmix_bridge_data(bridge_data->internal_rate, bridge_channel, 1);
}
+ /* If stat_iteration_counter is 0, then collect statistics during this mixing interation */
if (!stat_iteration_counter) {
gather_softmix_stats(&stats, bridge_data, bridge_channel);
}
- /* if the channel is suspended, don't check for audio, but
- * do continue to collect statistics */
+ /* if the channel is suspended, don't check for audio, but still gather stats */
if (bridge_channel->suspended) {
continue;
}
+ /* Try to get audio from the factory if available */
ast_mutex_lock(&sc->lock);
sc->have_audio = 0;
- /* Try to get audio from the factory if available */
if ((ast_slinfactory_available(&sc->factory) >= softmix_samples) &&
ast_slinfactory_read(&sc->factory, sc->our_buf, softmix_samples)) {
mixing_array.buffers[mixing_array.used_entries] = sc->our_buf;
mixing_array.used_entries++;
- /* Yay we have our own audio */
sc->have_audio = 1;
}
ast_mutex_unlock(&sc->lock);
@@ -642,8 +659,10 @@
/* process the softmix channel's new write audio */
softmix_process_write_audio(&trans_helper, &bridge_channel->chan->rawwriteformat, sc);
+
/* The frame is now ready for use... */
sc->have_frame = 1;
+
ast_mutex_unlock(&sc->lock);
/* Poke bridged channel thread just in case */
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